Method and Apparatus for Transmitting Data Between Wireless Devices in Wireless Communication System

1. A method for communicating between wireless devices in a wireless communication system, the method comprising: determining, by a first wireless device, a reference timing; determining, by the first wireless device, a transmission timing of a subframe based on the reference timing, the subframe including a plurality of Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbols; and communicating, by the first wireless device, directly with a second wireless device by using the subframe, wherein the reference timing is defined by a downlink reception timing for receiving a downlink subframe from a base station, wherein the direct communication between the first wireless device and the second wireless device uses an uplink carrier frequency of the base station, and wherein a last SC-FDMA symbol of the subframe is not used for the direct communication between the first wireless device and the second wireless device.

2. The method of claim 1 , further comprising: receiving, by the first wireless device, a resource allocation for the direct communication from the base station.

3. The method of claim 1 , wherein the downlink subframe uses a downlink carrier frequency of the base station.

4. The method of claim 1 , wherein the subframe for the direct communication uses an extended cyclic prefix.

5. The method of claim 4 , wherein the subframe for the direct communication includes 12 SC-FDMA symbols.

6. A device for communicating with a wireless device in a wireless communication system, the device comprising: a radio frequency (RF) unit configured to transmit and receive radio signals; and a processor operatively connected to the RF unit and configured to: determine a reference timing; determine a transmission timing of a subframe based on the reference timing, the subframe including a plurality of Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbols; and communicate directly with a peer device by using the subframe, wherein the reference timing is defined by a downlink reception timing for receiving a downlink subframe from a base station, wherein the direct communication between the device and the peer device uses an uplink carrier frequency of the base station, and wherein a last SC-FDMA symbol of the subframe is not used for the direct communication between the device and the peer device.

7. The device of claim 6 , wherein the processor is further configured to receive a resource allocation for the direct communication from the base station.

8. The device of claim 6 , wherein the downlink subframe uses a downlink carrier frequency of the base station.

9. The device of claim 6 , wherein the subframe for the direct communication uses an extended cyclic prefix.

10. The device of claim 9 , wherein the subframe for the direct communication includes 12 SC-FDMA symbols.